Application of ZrO2-Al2O3 aerogels to catalysts

ZrO2-Al2O3 aerogels were prepared by hydrolysis of metal alkoxides in alcoholic solutions and supercritical drying in order to obtain an improved de-NOx catalyst with high activity in a wide temperature range. The aerogels have about 20-50% higher activity than the xerogels in the range 300-600 degrees C. The higher activity of aerogels may be attributed to the higher effective gas diffusivity in them, estimated to be about 20-60 times higher than that of the xerogels, because of their high porosity and large pore size. The catalytic activity of aerogels containing 4-10 mol% ZrO2 is more than 20% higher than that of Al2O3 aerogels at temperatures <450 degrees C.